Wire duct



Sept. l1, 1956 F. ADAM 2,762,398

WIRE DUCT Filed Jari. 24, 1952 #norm/Ey@ United States Patent WIRE DUCT Frank Adam, St. Louis County, Mo., assignor to Frankv Adam Electric Company, St. Louis, Mo., a corporation of Missouri Application January 24, 1952, Serial No. 267,982 s Claims. (ci. 13s-15) with the ceiling surface of the lower story. v A pluralityof runs of such duct-work in side by side relationship were contemplated, one serving to accommodate the lighting circuit for the lower story, another serving to.

accommodate the telephone circuits for the next upper story, and another accommodating thefcircuit supplying the plug-in receptacles at or near the oor level of the upper story. With this arrangement, it was proposed that the side walls of the several duct runs be arranged to interit in tongue-and-groove fashion, and that the tongue of one and the groove of the other outermost duct would serve to key the several ducts into the concrete as the latter is poured about the ducts (which locally constitute the form on and about which the con` crete is poured). When there is but one run of duct, the tongueand-groove configuration may provide adequate anchorage but as the number of adjacent ducts increases the anchorage becomes less secure.

The object of the present invention generally stated is to improve upon the aforesaid arrangement, and particularly to provide a more secure anchorage of the ductwork in a poured concrete slab; and to render such ductwork useable with so-called hung ceilings where the duct-work is not embedded in concrete.

These and other objects of the invention, which will become apparent as the description proceeds, are accomplished by so conforming the trough member that the bottom of the trough (which becomes the top of the duct when installed) has a dovetail located wholly between the sidewise bounds of the trough but preferably extending depthwise for a greater distance than do the side walls. In the preferred form just mentioned, the exterior of the dovetail not only provides quite adequate anchorage in a concrete slab poured about it or with a.

correspondingly shaped bracket, but also the interior of the dovetail provides an anchorage for the reception, retention and facile repositioning of hangers for lighting xtures and the like.

Whether the dovetail extends outwardly, as in the preferred form, or inwardly, its location wholly betweenv the side-wise bounds of the duct not only provides the necessary anchorage with the support but strengthens the duct and makes possible the end-to-end connection on the exterior, without disturbing uniformity of the center-to-center spacing of runs vof duct in side-wise contiguity.

a 2,762,398 Patented Sept. 1 1, 1956` ice In the accompanying drawings:

Figure 1 is a perspective view of the duct composed of an open trough and cover therefor;

Figure 2 is an end view of three adjacent runs of duct supported in side-wise contiguity; v v

5 Figure 3 is a sectional view taken along line 3 3 `of Figure 2; 1

Y Figure 4 is an interior plan view of the trough sec-- tion of the duct shown in Figure 1 together wiha'iix-V ture hanger for correlation therewith; Y

Figure 5 is a perspective'view of the fixture hanger shown in Figure 4; and l t t Figure 6 is a perspective view of'a semi-sleeve for connecting pieces of the trough shown in Figure lin end-t -end relationship. Referring nowA to the drawings foran illustrative ern-l bodiment of the invention, the duct in the preferred form shown consists of a trough member 1 and a cover member 2. The trough member is formed of sheet metal bent to define two side walls 3 and 4 interconnected byl a bottom. The bottom in the embodiment shown consists of a plurality of parts 5 and16 which arezoifset from each other in the depthwise direction of the trough' 1.l The parts 5 of the bottom extend inwardly toward each other from the side walls 3 and 4 fora distance amounting,I in the embodimentshown, to about 20%A of the sidewise dimension of the trough and lare yintercon-- nected by the offset 6. A particular feature of the` pres,y

ent invention resides inthe arrangementofthe webs?v which connect the bottom parts, 5 with `the offset bottom; part 6. .The sidewise extent `of the part-,6 :isggreater lthan the distance between the inner edges-of parts` S.

Thus the part `6 substantially -overhangs the innermost increments ofl both parts 5. In the embodiment shown,

the arrangement is such that the .web 7, together withV part 6, form a dovetail.

Whether the overhanging offset of' the. bottom parts is disposed exteriorlyof the bottom parts 5 as shown,

or interiorly thereof, the overhanging relationship provides a key whereby the troughmay be` anchoredinto a supporting structure such as a ,slab of concrete or a.

metallic supporting structure; and `it also provides a pair of opposite interior shoulders rupon which ,a fixture hanger may be anchored.

In the formation of the trough 1, the side walls 3' and 4 are'preferably provided atabout their mid-sec-y tions with an inwardly projecting `bead 8v whichruns lengthwise of the side walls. The beads 8 in the respective side walls 3 and 4 are preferably arranged so as to be level with each other and are essentially disposed rather remotely from the free edges 9 and 10 ofil ,the side walls 3 and 4 respectively. Preferably the; beads 8 are located at least about a half-inchfrom the free edges 9 and 10.

The cover 2 is likewise formed 4of sheet metal and is provided at its opposite sides with resilient flanges 11,4

the upper extremities of which are turned outwardly to form lips 12 in position to engage behind the beads 8 of the trough 1 when the cover 2 is in position. Since the lips 12 are required to engage behind the beads 8, it is necessary that the flanges 11 vbe dimensioned Adepth-wise so as to slightly exceed the 'distance between the beads 8f and theedges 9 and 10 respectively. Accordingly, the more remote beads 8 be located from the edges 9 and 10,`

the longer ywill be flange 11 and the'greater the springiness imparted thereto. The importance of this feature resides in the fact that when the trough 1 is embedded in concrete, 'the side walls are precluded from yielding outwardly and consequently the cover and its adjunct partsmust be solely relied upon to provide the resilience necessary topermit lips 12 to passv over beads 8 in the process .of applying and removing the cover 2. YBy ar-l 3 ranging' the beads 8, is that. they Preis@ inwardly at .bath side walls, the over 2 may be applied Without regard to special orientation of the parts.

In situations where the trough 1 is laid bottom-iup on form wor-lc with the 'cover 2 i-nrplace2 a substantiahload applied downwardly on the duct {such as by ya lworkman stepping thereon `or the sudden dumping of ra .charge vof concrete thereon) may tend to drive the cover entirely within the trough by springing the'side walls, 3 and 4 outwardly as the latter are at that time not restrained against outward movement -fby the lrigidity of the final supporting structure, I-n order to avoid this occurrence,l spaced struts 13 are arranged to extend between the in-V teri'or of the cover 2 and the interior Vof the bottom parts 5. In the embodiment shown, the struts ljate provided in the form ,of a U-shaped bracket which is :secured :to the interior of :the cover at :suitable intervals lengthwise thereof. Thus upon the applicationvof a sudden load .of the character aforesaid sand before the ductis :anchored in t,the supporting .'structure, 'the free ends .of the struts 13 engage Athe interior of the bottom parts f5 and prevent the cover from being vforced within the trough 4as aforesaid The overhanging arrangement of the offset bottoni parts makes possible the easy end-to-end connection-o lengths of trough as by the application of the fitting shown fin :Figure 6. The iitting is a semi-sleever-h'a-ving parts 15 and 16 in overhanging Vdovetailed -relationship corresponding -to the 'relationship of bottom Aparts f5 'and 6 fof theltrough. Such a semi-sleeve may be telescoped over `the ends of the dovetaled section of two pieces of trough in =endtoend relationship. Such a semi-'sleeve may "then be secured tothe respectiveqpieces of vtrough in anydesvired Iway suchas the provision of a' small hole 17 in the bottom of the trough for snap-in engagement with 'an appropriately'positioned dimple 18 in the semisl'eeve. While a semi-sleeve of the Atype shown in Figure "6 may be applied on the interior of theA troughs, Vit is more advantageous to apply it on the exterior where it is open for inspection `before the concrete is pouredand Where it does not obstruct or reduce the passage-ways on the interior of the duct.

Instead of embedding the duct in concrete, thesame maybe suspended ybyany other suitable structure. One formY of suspending structure is illustrated in Figures 2 and 3 and consists essentially ofvagplate 2l! whoseilower edge 2,1 is. provided at intervals with` cut-outs 22 sized andshaped; to correspond with the contour ot thebottom-` parts 5,l and 6i and their interconnecting Webs 7 as above/e. described. In the form shown .'in `Figure 2, the,platesnllll is provided withthree such cut-outs in such spaced 'rela. tions'lip three. pieces `of the duct in sidewise .cone

tigity mayhek engaged andfsupportedfthereby. It will be: understood, however, that-.such platesl having but: two cntfouts .inntheir lower edge may be. used` in` multiple-for suppoting three or more adjacent duct runs. In-V the Qmltkqlpnt shovel,V the platel) is provided *with-` a l`t tingconnectionathereofato appropriate- .ill bennderstood that the -tiange23jmay y indiatedihereinbetore, the overhanging olset refr lafillitf si.; Wiesinger@ andi 6f fthe trough not' only, provides anchorage into ther supporting-pstwo. wie butlsofnrvidesf-Qn the interior-nf the. duets ,cen-s tement anchorage fg :fixture hangers and :the like. Such aviiitturehang f v ay be `in theform showmin Eig-A ureaib'r, of anyothert-form for engaging in thechannel; delnedbetween ktht-avoirs.7 and 'the bottom part `6. ln the form shown-in F igure 5A, ,a .plate 25 hasrdiagonally; opposite substantially square corners 2 6 and .27 and die, agonally .oppositerounded` corners 28'S andV 29. The didistance between corners28 and 29.` ,approx-v -mately thesame -as 'the.dstance between opposite webs' Zat vtheir juncturrwitlgihottom part @onlibe interior: oft

arcanos Y the @usla 111s diagonal distants between Corners. 26 and 27 is on the contrary considerably in excess of the distance between webs 7 at the position aforesaid. Preferably, the distance between edges 30 and 31 is slightly less than the distance between webs 7 at their junctures with bottom parts 5, while the distance between edges 32 and 33 is approximately the same as the distance between webs 7 at their jiunt-nre with bottom part 6. The

plate 25 may be cut out adjacent corners 28 and 2,9 to,

provideyieldablefingers 34 and 35 having some re- `siliency. Such a plate may be passed into the interior channel defined by webs 7 at any position along the length'thereof `so long 4as it is inserted with edges 30 and 31 parallel to the0 length of the duct .in the relationship shown in full lines'in'Figure 4. Once inserted into the channel, the plate 25 is turned into the position shown in dotted lines in Figure 4 where the edges 32 and 33 extend parallel to the length of the duct. The dimensions .of 'the plate 25 may .be so related to the interior dimensions of the dovetail in the trough that lingers 34 and 3Sy must yield inwardly in turning the plate between the v.positions shown in Figure 4 or alternatively, the plate 25 may be dimensioned so that it turns freely between the itwo said positions and then after it is disposed in the `anchoring position (shown in dotted lines in Figure 4)A a screw driver or other tool may be inserted behind thengers-34 and 35 to spring them out sufliciently to prevent'the plate from becoming dislodged.

The plate 25 is .provided in the form shown with an upset boss 36 which may be conformed to hold the headl of a bolt against turning or threaded for the reception of the customary fixture hanging fittings.

I-"rorn the foregoing description, those skilled in the art will readily understand the construction, operation and .advantages of the invention and realize that by providing the offset bottom parts which overhang well within theboundsdefined by Aside walls 3 and 4 an etective vanchorage with an exterior supporting structure is provided and fan eifective anchorage for an interior hanger is `prtwidcd without in any Wise impairing the ability t0 arrange a plurality of such ducts in side-Wise contiguity. Moreover, the overhanging offset relationship of the bottom facilitates `.the e-nd-to-end connection of pieces of duct collectively constituting a long run and makes Vpossible the application of connecting fittings in a position where they are exposed for inspection (prior to the .pouring of concrete) land ywitlzrout interfering with the unlormity of center to center spacing between adjacent ducts. ;While one complete embodiment of the invention has been disclosed in detail and some alternatives indicated, it is to bel understood that the invention isY not limited to the details of the foregoing disclosure but on the contrary that such modications and variations as do not depart from the spirit of the invention are, although notspecicaUy mentioned here, contemplated by and withinth'e scope ofV the appended claims.

Having thus vdescribed my invention what is claimed and desired to be secured by Letters vPatent is:

l. A duct comprising a sheet metal 4trough having a' bottom and opposite side walls, part of said bottom being oiset depthwise and in sidewise Ioverhanging relationship of Vsaid side walls, said flanges cach having yout-turned lips` which engage behind said beads and with the tree ed geshof the side walls respectively.

2. A duct comprising a sheet metal trough having a4 bottom and opposite side walls, part of s aidbo'ttorn being oiset depthwise andin sidewiseoverhanging relationship from another part thereof, said :side walls each having' a longitudinally extending inwardly projecting bead 1ooated substantially remote from the edge thereof, and a cover for said trough, said cover having anges at opposite sides thereof which enter said trough a depthwise dimension suihcient to extend beyond said beads when said cover is positioned adjacent the outer edges of said side Walls, said anges each having out-turned lips which engage behind said beads and with the free edges of the side walls respectively, and -struts on said cover extending into engagement with one of the parts of said bottom.

3. A duct comprising a trough having a bottom and opposite side walls, said side walls terminating in a free edge remote from the bottom, at each side thereof, and

a cover for disposition acros-s the space between the free edges of said side walls in spaced realtionship with said bottom, each of said side walls having an inwardly projecting bead substantially remote from its free edge, and said cover having at each side thereof a substantially long yieldable pmt which enters said trough and engages be- .hind said beads respectively and overhanging corner portions engageable with the free edges of said side walls.

References Cited inthe le of this patent UNITED STATES PATENTS 800,055 Ayres Sept. 19, 1905 1,189,208 H'odkinson June 27, 1916 1,201,420 Agricola Oct. 17, 1916 1,277,550 Connell Sept. 3, 1918 2,356,309 Garbe Aug. 22, 1944 2,463,057 Runge Mar. 1, 1949 2,485,090 Finch Oct. 18, 1949 2,523,869 Fleming Sept. 26, 1950 2,559,639 Kruger July 10, 1951 2,564,362 Holden Aug. 14, 1951 2,595,487 Runge et al. May 6, 1952 FOREIGN PATENTS 483,589 Great Britain Apr. 22, 1938 

